Electric incandescent lamp and method of manufacturing its illuminating body



UFACTURING ITS Feb. 21, 1928.

F. SKAUPY ELECTRIC INCANDESCENT LAMP AND METHOD OF MAN ILLUMINATING BODYFiled Dec. 2,

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Patented Feb. 21.1

UNITED STATES PATENT, OFFICE.

FRANZ SKAUPY, OI BERLIN, G, ASSIGNOB TO GENERAL ELECTRIC A CORPORATIONOI NEW YORK.

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Application filed December 2, 1821, Serial No. 519,400, and in GermanyDecember 4, 1920.

This invention relates to an electric i ncandescent lamp in whichtransparent bodzgs which are as free of turb1 ess or dimness as possibleand are colored preferably cor responding to that portion of thespectrum which in its turn corresponds to the rays to be emitted arecaused to glow. As in most cases these bodies themselves are notsufiicientl metal ic conductor that serves as carrier for the currentand transfers the current-heat to the transparent part of theillummatlng body, the union'being effected in a manner ensuring goodtransfer of the heat, preferably by applying the metallic conductor tothe transparent conductor in the form of a thin small layer either uponthe outer surface or, if the transparent conductor is of tubular shape,upon the. inner surface of the same also. As a metallic conductor has acomparatively uneconomical radiation which extends over all portions ofthe spectrum including some which are undesirable, its radiating surfacemust be as small as possible in order to make its rays practicallyinsignificant in comparison to those of the transparent colored part ofthe illuminating body and to make it serve mainly for thecurrentconduction and the heat transference, so that the chief amount ofthe radiation issues from the transparent part. The metallic conductor,in. order to be able to transfer the heat as uniformly as possible toall portions of that transparent part should not be too distant fromanyportion of the illumihating body. That is attained best by making themetallic conductor form a spiral upon the transparent partilthearrangement being then preferably suc that the axis of the spiralcoincides with the axis of the illuminating body.

In devices of the prior art either opaque metallic or opaquenon-metallic illuminating bodies for instance oxidic bodies, have beenused, the main radiation of which, with the temperatures mostlyemployed, lies for the greater part in the invisible portion of thespectrum, whereby the greatest part of the energy spent is consumed inthe production of rays of an undesirable wave length. But lampsmanufactured according to the present invention. have a pure or nearlypure selective radiation which is the more economic the lesstheilluminating substance conductive, they are united with a em loyedabsorbs and emits waves of an un esirable length and the smaller theradiating surface of the metallic conductor is by which the current heatis transferred. It might, thus, on principle, be possible to produce anearly absolutel economic lamp in which nearly the totaf ener spent istransformed into radiation of the esired wave length, that is to say(apart from special cases where invisible light, for instance ultra-redlight, is to be converted) into visible light.

The trans arent substances existing in nature or capa le of beingmanufactured in a chemical way, are unsatisfactory because they emitlight of an undesirable wave length and contain turbidities, impuritiesof the electric and the like which radiate dark waves.

Nevertheless, there may substances be found 'which are sufliciently freefrom this drawback and yield a satisfying output of li ht, especially ifv such substances are suita ly colored by admixtures of slightquantities of substances of another color. To prevent the coloringsubstances from rendering the trans parent substance opaque, they musteither alreadyexist in their base substances in the form of a solidsolution or an isomorph admixture or in a highly dispersed colloidalstate, especially near to and at the surface of the respectivebase-substances, or must be applied to the outer surface of the same.

My invention contemplates the use of iioilerate temperatures of theilluminating or y. To obviate structural changes of the illuminatingbody by the high temperature whereby the transparency would bediminished and the illuminating effect changed, as easily occurs withglassy substances or with substances forming small crystals, thetransparent part of the illuminating body may be manufactured, accordingto this invention,

from one crystal or from a few crystals or 7 crystal pieces, similarlyas done with the Wolfram crystal thread in the manufacture ofincandescent lamps, One chooses crystals that are free from turbidnessor dimness, also as free as phenomenon, an colored by admixtures andshaped as desired and required, by melting. To manufacture them, similarmethods ma advan- V tag eously be employed as are m e use of cpossiblefrom the Tyndall I transparent; they may be for the manufacture ofartificial precious stones, for instance rubies. Or pulverulentsubstances may be pressed to form little bars which are heated to such ahigh temerature as to completely sinter-until they come transparent. Theheating is pref erably carried through in a vacuum, either by means ofan external source of heat, for instance an electric furnace, or byelectric heating of the little bar itself which is rendered conductiveeither by pre-heating it or by a heat-conductin connection with a metallic conductor. his latter may be the same as that serving in thefinished lamp for transferring the current heat. If the bar itself ismade conductive, substances a purpose in trides, carbi es, sulphides,flourides, and esmay be added which first increase its conductivity andthen evaporate at, high temperature. The heating is in such a caseefl'ected preferably by alternating current of a rather high frequency,of the order em-' ,ployed in wireless telegraphy, the purpose being toobviate electrolytic phenomena. The

resulting transparent body should, from obvious reasons, be as free aspossible from electrolytic conduction. In' cases where a certainconductivity of thetransparent body cannot be obviated, the metallicconductor is preferably arranged in the form of a few axial stripseither upon the surface of its base or within this latter, the axialstrips being in either case connected in parallel with each other. v

As transparent substances suitable for the uestion, heat-proof oxides,ni-

pecially' such substances as oxide of thorium, oxlde ofi-scandlum, oxldeof magnesium, and

the like may be em loyed; furthermore the corresponding nitri es, alsoboron-nitrogen. As coloring substances suitable for the purpose inquestion ma be employed fire-proof oxides, such as oxi e of cerium,especially, however, substances which in a thick layer show metallicbrightness, but-are transparent and colored in a thin layer, as is thecase with the nitrides of titanium, zirconium, some low oxides, such asthat of titanium, but also with certain metals themselves.

The metallic conductors which are the intermediaries for the transfer ofthe heat to the transparent substance consists of metals or conductivecompounds of high fusing point, such as tungsten, osmium, tantalum graphite, titanium-nitrogen, and the like. he layers or coatingsconsisting of them, for instance spirally wound coatings, may be made byap lying to the transparent substance a colloi al solution of therespective conductor in the form of a small stri and then heating thewhole body in' a suitable atmosphere in order to sinter it. Instead ofthe colloidal solution of the conductor a the respective substance maybe ma e use of,

for instance colloidal Wolfram acid, and the coating may be subsequentlyconverted into metal by. heating it m a reducing atmosphere. Coatings ofthe kind in question may also be applied by cathodic dispersion.

The coatings may also be applied by those ting body; and Figure 3 isalso a similar illustration showing a third form of execution.

Referrin bar of oxi e of thorium is provided with a spirally shapedcoating or layer of tungsten or osmium, the ends of which areconductively connected with the feed wires 3 and 4 of the bar 1. Thespaces between the con- .volutions of the spiral 2 and the bar 1 arecovered with a. thin transparent coating or to Fig. 1, a transparentlittle layer of titanium-nitride. The ends 6 of the illuminating bodyare appropriately thickened in order to prevent the feed wires frombecoming as hot as the effective'parts of the illuminating body, becausesaid ends, otherwise, would radiate away too large an amount of energyFor the rest, concerning the connection of the feed wires with theilluminating body, for instance with themetallic.

layer of this latter, all the methods known in connection with themanufacture of Nernst-lamps may be employed. 1

If the transparent base substance of the illuminating body, whichcarries the metallic conductor, is not or cannot be, suflicientlycolored, transparent colored substances of macroscopic dimensions may beembedded into, or made to contact with the outside of it. Severalsubstances of different colors may be embedded into the same basesubstance, those substances emitting them, according to their colors, acorrespondin l differently colored light whereby particul effects may beproduced.

Corresponding to the chemical proper- .ties of the illuminating body thesame may be made to light in the free air, in evacuated vessels or invessels filled with gases of the proper kind. The bulbs are filled withgases that are bad conductors of heat, for instance argon gas and.thelike, or with a as for instance nitrogen, which counteracts y itspartial pressure the dissociation of the substance of the illuminatingbody, especially in the case where a nitride forms part of theilluminatin body.

The conductor whic transfers the heat may be a wire, if it is broughtinto suitable heat conducting relation with the transparent substance bybeing melted or pressed into, or being made to contact with the outsideof it. p,

As the illuminating bodies constructed according to this invention emitin most cases per unit of surface a by far lesser amount of energy thando the known illuminating bodies of incandescent lamps, they may beconsiderably larger thanthese latter,

. concerning their breadth, as well as their thickness. And as thecurrent is supplied not through'the transparent main portion of theconductor, but through the metallic conductor, the former may have themost varied forms; it may be a disk,-a ball, a figurativerepresentation, writing characters of any kind, and the like, andthevarious trans arent parts ma be made to light with. diferent colors. 2.mild, not dazzlin light and is in this respect somewhat similar toelectric gas lamps with glow discharge. p

V Fig. 2 shows a lamp, the illuminating body of which is a lens-s apeddisk 7 around which the current conductlng layer runs in aspirally-shaped way. The lamp shown in Fig.3 has an illuminating bodywith parallel axial strips 8. No potential difli'erence can arisebetween these strips and, conseuently no transverse current can pass trough the illuminating substance.

I claim:

1. In combination, a body which when heated-radiates selectively'andwhich is substantially transparent to waves differing from thoseradiated, and means for heating said body to cause it to so radiate. J

2. In combination, a body which when heated radiates selectively andwhich is substantially transparent to waves differing from thoseradiated, the major portion of the selective radiation falling withinthe visible range of the spectrum and means for heating said body tocause it to so radiate.

3. In combination, a body in macro-crystal form which when heatedradiates selectively and which is substantially transgarent to wavesdiffering from those radiate and means for heating said body to cause itto so radiate.

4. In combination, a body in macro-crystal form which when heatedradiates selectively substantially'the major portion of the energyimparted to it by heating, and a device for heating said body to causeit to so radiate.

5. In combination, a body which when heated radiates selectively, saidbody being clear and in macro-crystal form, and means for heating saidbody to cause it to so radiate.

6. In combination, a body which when heated radiates selectively, saidbody being in transparent macro-crystal form, the major portion of theselective radiation falling t any rate, the lamp emits within thevisible range of the spectrum, and means 'for heating said body to causeit to so radiate. Y

7-. In combination, a body having the form of a. transparentmacro-crystal, and having the propert of selectively radiatin li ht whenheate means supported by said rst body for heating the latter to causeit to so.

radlate.

8. In combination, a bod in the form of a clear macro-crystal, said yhaving the property of selectively radiating li ht when heated, meanssupported by said body for heating the latter to cause it to so radiate.

9. In combinatiomfa'clear body which when heated radiates selectively,and electric means for heating said body to cause it to so radiate.

10. In combination, a .bod which when heated radiates selectively anwhich is substantially transparent to Waves difiering from thoseradiated, and means for heatin said body to cause it to so radiate, saidbody consisting of athorium com ound.

' 11. In combination, a bod w ich when heated radiates selectively anwhich is substantially transparent to waves differing from thoseradiated, and means for heatingsaid body to cause it to so radiate, saidbody consisting of an oxide of a metal.

12. In combination, a body which when heated radiates selectively, andwhich is substantially transparent to waves differing from thoseradiated, and means for heating said-body to cause it to so radiate,said body consisting of a com ound of one of the metals which has a higfusing point. 13. In combination, a transparent body, a second body inintimate thermal contact with said first body, which second body whenheated radiates selectively and is substantially transparent to wavesdiffering from those radiated, and means for heating said first body tocause it to heat said second body to cause the second body to soradiate.

14. In combination, a transparent body, a second body supported by saidfirst body, which second body when heated radiates selectively and whichis substantially trans parent to Waves difi'erin from those radiated,and means for heating said first body to cause it to heat said secondbody to cause the second body to so radiate.

15. In combination, first a transparent body, second a body in intimatethermal contact with said first body, which second body when heatedradiates selectively and is substantially transparent to waves difieringfrom those radiated, and means for heating said first body to cause itto heat said second body to cause the second body to so radiate, saidsecond body consisting of a metallic oxide.

16. In combination, first a transparent body, second a body in intimatethermal contact with said first body, which second body body, second abody in intimate thermal contact with said first body, which second bodywhen heated radiates selectively and is substantially transparent towaves differing from those radiated, and means for heating said firstbody to cause it to heat said second body to cause the second body to soradiate, said second body consisting of a substance which in a thicklayer has a brilliant metallic color and which in a thin layer is trans:parent and colored.

18. In combination, first a transparent body, second a body supported bysaid first body, which second body when heated radiates selectively andwhich is substantially transparent to waves differing from thoseradiated, and means for heating said first body to cause it to heat saidsecond body,

to cause the second body to so radiate, said second body consisting of asubstance which in a thick layer has a brilliant metallic color' andwhich in a thin layer is transparent and colored.

19. In combination, first a transparent 17. In combination, first atransparent body, second a body in intimate thermal contact with saidfirst body and which when heated radiates selectively the major portionof the energy imparted to it by heating, and means for heating saidfirst body to cause it to heat said second body to cause the second bodyto so radiate.

'21. In combination, first a transparen .body, second a body supportedby said, first is volatile at high temperatures to render a the materialconductive and in passing a high frequency alternating current throughsaid material until it is sintered and heating until the conductingsubstance volatilizes.

23. In combination, a body which when heated radiates selectively, andwhich is substantially transparent. to waves differing from thoseradiated, and means for heating said body to cause it to so radiate,said body consisting of a compound of one of the refractory metals whichhas a high fusing point.

24. In combination, first a transparent body, second a body supported bysaid first body, which second body when heated radiates selectively and.which is substantially transparent to waves diflerin from those.radiated, and means for heating said first body to cause it to heatsaid second body to cause the second body to so radiate, said secondbody consisting of cerium oxide.

In testimony whereof I aifix my signature.

FRANZ SKAUPY.

